


Keep It A Secret

by SmileAndASong



Category: Marvel, Marvel Cinematic Universe
Genre: Domestic Fluff, Family Feels, Family Fluff, Fluff, Halloween, Halloween Costumes, Kid Fic, M/M, Misunderstandings, Secrets, Superfamily, Superfamily (Marvel)
Language: English
Status: Completed
Published: 2018-10-31
Updated: 2018-10-31
Packaged: 2019-08-11 06:55:09
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,258
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16470875
Author URL: https://archiveofourown.org/users/SmileAndASong/pseuds/SmileAndASong
Summary: Tony decides to surprise Steve by having Peter dress up as Captain America for Halloween. Steve decides to surprise Tony by having Peter dress up as Iron Man for Halloween. Peter now has two secrets to keep, two costumes to wear, and two loving fathers that he doesn't want to disappoint.





	Keep It A Secret

**Author's Note:**

  * For [avengersandco](https://archiveofourown.org/users/avengersandco/gifts).



> This was written for the SteveTony Halloween Exchange for superhusbandswithasideoffamily who requested Superfamily and a happy ending! This is my first time writing Superfamily, and I am not overly familiar with this aspect of the Steve/Tony fandom, so I hope it came out alright!
> 
> It's still pretty on brand for my usual fic writing, meaning it is EXTREMELY fluffy, which I hope fits what you had in mind for your request. I also hope you don't mind some shallow horror movie references that I allowed myself to indulge in.
> 
> This was a lot more fun to write than I had anticipated it being. I definitely loved getting to write a fic with a  
> As always, thank you for taking the time to read. And more importantly, have a very happy Halloween!

“Peter, what do you want to be for Halloween?”

The six year old boy perked up at his father's mention of the upcoming holiday. He loved Halloween, it was easily one of the best holidays. The candy, the costumes, the awesome party that his parents put together every year, it was just the best! The holiday was only about a week and a half away though, and Peter couldn’t figure out what he wanted to be. 

“I don’t know…” Peter mumbled, handing his father a wrench from the tool box. It was a Saturday afternoon which meant he was playing assistant to his father in the lab, one of his favorite weekend traditions.

Tony took it with a thanks, and used it to tighten something on the new gauntlet he was working on. “Well, you gotta have at least some sort of an idea. What about a ninja turtle?”

Peter rolled his eyes. “Daddy, ninja turtles are for kindergarteners. I’m in first grade now.”

Tony snorted. “Right, right, how could I possibly be so ignorant?” Tony put the wrench aside and examined the gauntlet. Seeming pleased with it, he slid it off for the moment and devoted his full attention to his son. “Well I don’t know, educate me then! What’s cool with first graders these days?”

“Star Wars!” Peter said excitedly.

“Hmm...I could make you stormtrooper armor? That would be pretty cool, right?” Tony suggested.

Peter at first seemed very interested in the idea, beaming at the prospect of having stormtrooper armor that looked right out of the movie (because if anyone could make film accurate armor, it was Tony Stark). But then he remembered just /how/ many of his classmates also expressed interest in being troopers. They’d have a whole army at this rate, and he wanted to stand out. 

“A lot of other kids in class are going to be troopers,” Peter began. “I don’t wanna wear the same thing as everyone else. I want to be someone really cool! Who do you think is the coolest person that I could be?”

“Oh come on, you know that - your father is the coolest, of course!” Tony paused, a wide grin forming on his face. It was the same grin Peter recognized as his ‘genius idea’ one. “That’s it, Petey! Oh man, you should be Captain America for Halloween. I can make you your own shield and a miniature version of the suit I just made Steve! You’ll be adorable, and Papa will just love it.”

“Yeah!” Peter agreed eagerly. “That’s a great idea, and I get my own shield? Can I throw it in the house?”

“No, absolutely not,” Tony said immediately, his response making Peter pout. “But outside, sure.”

Peter’s grin quickly returned. “Alright, deal.”

“You know what would be really cool? Let’s keep it a secret from Papa! We can surprise him at the big Halloween party,” Tony suggested. “I think he may actually die seeing you dressed like him, especially if he’s not expecting it.”

Peter’s smile faded a bit. Secrets were always hard to keep, especially one that exciting and for that long. But his Daddy was so excited about the surprise, he couldn’t let him down. “Okay, I’ll keep it a secret.”

Tony smiled, ruffling his hair. “Good. I’ll start working on the suit right away. I’ll let you know when it’s ready, alright?”

“Peter! Tony!” Steve’s voice called from up the stairs. “Lunch is ready!”

Tony moved out of his stool and helped Peter out of his. Just as they were starting to walk out of the lab, a warning siren came from the main computer. Tony reacted quickly, and rushed over to check it. “Crap.” Tony looked back to Peter. “I got some unstable parts on one of my projects I need to take care of, tell Papa I’ll have lunch a little later.”

Peter nodded. He was hardly phased by the unstable parts conundrum, implying that it probably happened on a somewhat frequent basis. “Alright, Daddy.”

“And Peter? Remember, don’t tell Papa about your Halloween costume.” Tony jumped, as another siren went off loudly from the computer. “...or the unstable parts.”

Great. Two secrets for Peter to keep now. He gave Tony a thumbs up, which his father returned, before he made his way up the stairs and out of the lab.

 

XXXXX

 

“Did I hear alarms going off down there?”

Peter looked up from his grilled cheese sandwich at Steve’s question. He shook his head. “No, uh, Daddy was watching those crime shows he likes while we were working.”

Steve raised an eyebrow. “Right, of course.” He joined Peter at the table, clearly seeing through that lie. Peter only hoped that Steve wouldn’t figure out the Halloween costume one though. Maybe he wouldn’t even bring it up.

“Have you figured out what you want to be for Halloween, Petey?”

Peter thought of one of the curse words he often overheard Tony say under his breath, the ones that he always had to swear he would never say (but thinking them was something different entirely). “Uh, no, no ideas at all! I think maybe I won’t dress up this year. I am six, that’s kinda old for Halloween.”

“Nonsense! I’m in my nineties and I’m still dressing up for Halloween. I think you can definitely get away with it being six,” Steve encouraged.

Peter smiled weakly. “Well, maybe I can be a stormtrooper. I can ask Daddy to help me make the armor.”

“That’s a good idea. If there’s one thing your father knows, it’s how to build armor.” Steve froze for a moment before a grin formed on his face, a grin was very akin to the one Tony had worn mere moments earlier. “Armor...that’s it! Peter, I’ve got a great idea. What if you were Iron Man for Halloween? Your father would absolutely love it! We can make you an Iron Man suit and surprise him. Wouldn’t that be fun?”

If Peter ever had any doubts about how perfect his Dads were for eachother, they were completely gone now. What were the odds that they would both have the same exact idea within the same hour? Peter considered lying and trying to push his desire to be a stormtrooper more, but the look of sheer joy on Steve’s face made that impossible. No way could he let him down too.

“Yeah, that would be a lot of fun.” Peter agreed somewhat reluctantly. “But do you even know how to make armor? I mean, I know a little from what I see Daddy do in the lab, but I couldn’t go in there without him knowing or figuring it out.”

Steve waved a dismissive hand. “Your father isn’t the only one good with his hands. I’m sure I can definitely put something together. Bet there’s something on Pinterest about making an Iron Man costume.” Some of the mothers of the kids in Peter’s class had told Steve about Pinterest, and he quickly became obsessed. Steve was definitely very good at being domestic, but also still excellent at being a kickass superhero. It was an interesting contrast. “We can start working on it after school, before Daddy gets home from his work at the office. And remember, we're going to keep it a secret from him.”

Peter forced a weak smile. “Cool! I can’t wait to get started.”

How was he going to keep both secrets? How was he going to somehow be Iron Man and Captain America at the same time? 

Suddenly the idea of skipping Halloween and going right to Thanksgiving was becoming very attractive to the nervous six year old. 

XXXXX

“Peter! Come down, the guests are going to be here soon!”

Peter looked to his doorway at the sound of one of his Dads beckoning him over. The party was starting in just a few minutes, meaning it was time for the big reveal. He started to make his way out the door but stopped to take one last look at himself in the mirror.

And it definitely was...something, alright.

At his innermost layer, he wore a very authentic looking Captain America costume. It was the same bold and striking colors as his father’s, and perfectly accurate from the top of his cowl to the tip of his red boots. Tony even made it out of the same Kevlar-blend fabric for the sheer sake of authenticity; it was definitely a bit ridiculous to put that kind of money and time into a Halloween costume for a six year old, but Tony Stark was no stranger to the outlandish. Peter’s Captain America costume was also outfitted with a small shield, though of course not made from the same vibranium. Instead, it was a more lightweight but still durable material. 

As lovely as his Cap costume was, a good portion of it was blocked by his /other/ costume: His Iron Man costume.

The Iron Man suit had been constructed by him and his Papa from scratch out of various pieces of cardboard and paper mache. Unfortunately, it didn’t quite come out like the DIY Costume tutorial said it would. He was covered in clunky pieces of red and gold cardboard fastened all over his body, all adorned with an absurd amount of glitter glue that was supposed to give it the 'shine' of the Iron Man armor.

The 'best parts' of the costume were by far the small piece of tupperware at the center of his chest that was painted blue to be his ‘arc reactor’, and the Jason Vorhees mask purchased from a Halloween store that was painted over to resemble an Iron Man mask. In Steve’s defense, painting was his strong suit, so the ‘mask’ did mimic Iron Man’s pretty well, despite all of the holes in it from its previous use as a hockey mask. 

Cardboard construction and paper mache, however, were not Steve’s area of expertise. Peter had already used tape for ‘repair’ in several areas - and all he had done so far was put the armor on! How was he supposed to walk in this? He felt ridiculous, and he knew his fathers were going to think so too. 

What if they got angry at him for ruining all of their hard-work by wearing them both together? His Daddy had spent so much time and money on his suit, and his Papa did so much research on craft tutorials. He didn’t want to insult their efforts. Or maybe they’d just laugh at him for how stupid he looked; that would definitely be worse. They’d probably kick him out of the party, maybe even the house, for looking and being so stupid. 

“Peter! Is everything okay?”

Peter sighed. It was now or never. “Coming!” Peter called out, sliding on his Iron Man mask in a way that did not completely cover his cowl. He took a deep breath and headed out to join his fathers. 

He was so nervous he didn’t even notice his leg armor fall off after taking just one step toward the door.

 

XXXXX

 

Steve and Tony were in the center of the room when Peter walked in. They were pretty preoccupied with the decorations, so they didn’t immediately notice his presence. 

“I can’t wait to shave this thing off tomorrow…” Peter heard Steve say in reference to the beard he had grown out pretty quickly for his Wolfman costume. From what Peter could see, they added some extra hair on top of the beard as well, making it extra fluffy and fun. 

His Daddy chuckled in response. “Oh, but you looked so good all hairy like this! And Dracula definitely loves a good werewolf…” Tony pressed in closer to Steve, draping the dramatic black cape of his vampire costume around the two of them and stealing a kiss. He smirked, the fake plastic fangs protruding out as he did. “I could get used to kissing the beard, y’know.”

Steve smirked. “Well you better get your kisses in while it’s still here, Drac…”

Peter winced as they kissed again, this one far longer and grosser. The true horror of Halloween was definitely watching his fathers act all lovey-dovey together, and that unfortunately didn’t end when November began. Before the kiss could turn into a full on makeout session, Peter decided to make his presence known. “Uh, hi?”

Steve and Tony jumped at the sound of the voice, and looked in Peter’s direction in unison; the synchronization of their actions did not stop there. First, they both looked at him in sheer confusion as to what he was wearing. Then they turned to look at each-other, silently searching for an explanation. Then they looked back at Peter and the boy’s fears came true.

They burst out laughing.

Steve looked back to Tony, still laughing. “Did you tell Peter to dress up like Cap to surprise me?”

Tony nodded, his laughter calming down just enough to respond. “And did you tell Peter to dress up like Iron Man to surprise me?”

Steve nodded. They began to laugh even louder than before, and Steve’s howl-like laughter was actually very appropriate for his costume. 

“I knew you were going to laugh, I just knew it!” Peter ripped off his Iron Man mask, throwing it on the ground “I get it, I look like a big dumby! I don’t want everyone else to laugh at me, and I know I look too stupid to come to the party. But can I at least stay in my room? I don’t wanna get kicked out of the house…” He sniffled, his six year old emotions starting to get the best of him.

Once the first sniffle came out of Peter, Steve and Tony immediately stopped laughing and completely shifted to concerned and doting parent mode. Keeping with their unison, they both knelt down beside Peter to be at eye level with him.

“Oh Peter, do you really think we would kick you out over a Halloween costume?” Steve asked Peter, who simply shrugged. Steve smiled, wiping the few tears that slipped out away. “We would never kick you out, not ever. Especially not when you’re going to have the best costume at the party!”

“But you were laughing at me, both of you were...you were making fun of me,” Peter mumbled, though leaned into his Papa more once a comforting arm slid around him.

Tony’s arm slid on his back, over his cardboard armor. “Honey, we weren’t laughing at you. We were laughing at the situation. Because what are the odds that we would both want to surprise each-other by having you dress up as our respective superheroes?”

“Pretty likely when you’re in love, I guess,” Steve said sweetly, his other arm wrapping around Tony so the three of them were embracing.

Peter winced. “Don’t make it gross, Papa.”

Steve chuckled, though Peter relaxed this time in knowing that it was not laughter /at/ him. “Let me see you,” He gently examined the suit underneath the armor he was already familiar with, running his fingers over the material. “Oh look how handsome and heroic you look, and you even have a shield too! A true supersoldier in the-...Tony, did you make this out of the same material as my suit?”

Tony grinned sheepishly. “I wanted to go for authenticity. Now if there’s a fire, he’ll be safe?” Tony tried, but was quick to change to subject before Steve could say anything more. “Alright, let’s take a look at your armor!” 

Peter shifted his attention toward his Daddy. His Daddy grinned eagerly at him, and spent what felt like an eternity admiring every last detail of Iron Man armor; Tony Stark was a sucker for detail. 

“It’s perfect. Did you and Papa make this together?” Tony asked, picking up the Iron Man mask and sliding it back on his son.

“Yeah!” Peter said eagerly. “I cut out all the cardboard pieces myself! Papa did most of the painting though, you know he’s good at painting.”

“Oh yes, very aware,” Tony said in a suggestive tone that went right over Peter’s six year old understanding (Steve still shoved him for it though). “It’s extra special because you did it together. And I can shove my ego aside enough to admit that the Iron Man armor is definitely better than the Cap costume I made. Still me, so I guess my ego can is fed nonetheless.”

“No,” Steve interjected quickly. “The best costume is how Peter is wearing it right now: Iron Man and Captain America together.”

“That’s right,” Tony agreed, looking at his son fondly. “Our being together is what made us adopt you after all. We’re a family because of you, baby.”

“Captain America and Iron Man are two very strong superheroes. And they are even stronger together when they are Captain Iron Man! Secret identity: Peter Rogers-Stark. The strongest Avenger of them all!” Steve stated proudly.

“No one can be Captain Iron Man but you,” Tony told Peter. “You represent our love for each-other, which is stronger than any super serum or repulsor ray could ever be. You are the best of us both, you /are/ Captain Iron Man.”

Peter beamed at his fathers’ words. He felt silly for how worried he had been earlier, but now he felt proud standing in both his million dollar supersuit and his crafty intricately cut recycled cardboard. 

He wrapped his clunky cardboard arms around both of his fathers and clung to them tightly. “I love you, Papa. I love you, Daddy.”

“And we love you, Captain Iron Man,” Tony and Steve said together. 

Tony snorted at his husband speaking in time with him. “We’ve been spending too much time together.”

“You’re telling me,” Steve teased, standing up and scooping Peter up with him. “Which is why I want to spend the party with the person with the coolest costume. Fortunately, he’s already here and in my arms.” 

Tony huffed, feigning offense. “Captain Iron Man wouldn’t leave me out in the cold though. Do you have room for one more in your entourage tonight, Mr. Superhero? I might get angry and start drinking your blood if you say no though!” Tony leaned in and pressed his fake fangs into Peter’s neck, while simultaneously tickling his belly, and Steve joined in with the tickling right after. 

Peter roared with laughter, squirming in his Papa’s arms. “Okay, okay! You can hang out with us, Daddy. Stop, stop!” Peter’s giggles subsided once the tickling stopped. His attention shifted when he heard the familiar voice of the A.I. alerting them that the first guests had begun to arrive. 

“Ready to commence Mission: Halloween Party, soldier?” Steve asked, setting Peter back down on his feet.

Peter stood up proudly, placing his hands firmly on his hips in a way that mimicked the superhero stance of both his fathers. He stood with a clear confidence, and any reservations he had earlier were completely gone. He knew who he was now. He was a superhero. He was the manifestation of the love of the two of the greatest heroes ever; the ones the world knew as Iron Man and Captain America, but the ones he was lucky enough to know as ‘Daddy’ and ‘Papa’. And only he could do the job of representing that powerful love.

Only he could be Captain Iron Man.

Peter saluted his Papa proudly. “Mission is a go for Captain Iron Man!”

Hopefully, it would be the first of many successful ‘missions’ for the young superhero.


End file.
